The present disclosure provides a method for transmitting an uplink signal, a terminal device and a network device. The method includes the following steps. The terminal device receives resource configuration information carried by a RRC message. The resource configuration information is used to indicate a plurality of resources configured for zero-power DMRS. The terminal device receives activation information carried by DCI. The activation information is used to indicate: 1) whether to enable the zero-power DMRS; and 2) selecting a resource occupied by the enabled zero-power DMRS in the plurality of resources. The terminal device determines he resource occupied by the zero-power DMRS based on the resource configuration information and the activation information. The resource occupied by the zero-power DMRS is not used for sending uplink data, and the resource occupied by the zero-power DMRS is not used for sending non-zero-power DMRS.